Portable computing is increasingly important in many environments including home and business contexts. Important portable computing capabilities include worldwide roaming, location based services, RTC on the go and the like. Improvements in computer and network architecture and functionality have continually improved the user experience. For instance, handoff, security, and session continuity are important for roaming. VLAN support can be used for guest access. Currently, however, certain areas of computing technology fall short and prevent users from having full and rich experiences in portable computing scenarios. For example, despite improvements in battery technology, users are still frustrated by the inability to use the laptop for an extended period of time without having to charge the battery. The lack of duration for portable devices is a prevalent and continuing problem and leads to user frustration, loss of productivity, and lack of technology adoption by users.
Thus, despite the improved power source technologies, concomitant improvements in power consumption are also needed to improve power duration and user satisfaction. The display or monitor of a computing device is often the most-used output device and is also often the greatest power consumer. Most desktop displays use a cathode ray tube (CRT), while portable computing devices such as laptops incorporate liquid crystal display (LCD), light-emitting diode (LED), gas plasma or other image projection technology. Because of their slimmer design and lesser energy consumption, monitors using LCD technologies are the most common in laptops and are beginning to replace the venerable CRT on many desktops. The LCD display can be a very power hungry component of a portable computing device, consuming as much as one third of the overall power being consumed. In fact, LCD displays consume on average between 30 and 40 watts.
Many LCD displays are “active-matrix” and depend on thin film transistors (TFTs). Typically, TFTs are arranged on a glass substrate in a matrix configuration, so that activating an individual pixel corresponds to switching on a particular row while sending a signal down a particular column. A capacitor corresponding to the pixel is thus charged and holds the charge until the display is refreshed. A polarizing crystal for the pixel is activated by the capacitor's charge and allows light to pass through from behind. Varying degrees of pixel brightness can be achieved by varying the voltage to which the capacitor is charged; the polarizing crystal allows more or less light to pass depending on the voltage supplied. The power consumption of an LCD display is due primarily to the pixel writing technique described above as well as to backlighting that is used to light the display.
Thus, although innovations have been made to provide longer-lasting batteries and to lessen the power consumption of portable devices, existing technology still does not allow for adequate device duration nor does it allow adequate user management of power conservation features.